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Biomedical subjects

E László

Publications and source records attributed to E László.

18 recordsLinked to original sources
PubMed2002

Blast colony-forming cell binding from CML bone marrow, or blood, on stromal layers pretreated with G-CSF or SCF.

Blast colony-forming cells (CFU-BL) represent a specific subpopulation of special primitive progenitors characterized by colony formation only in close contact with a preformed stromal layer. CFU-BL derived from bone marrow of chronic myeloid leukaemia (CML) patients have been proved to adhere poorly to bone marrow derived stromal layers suggesting that the appearance of progenitors and precursors in the circulation is due to a defective adhesion of these cells to the bone marrow microenvironment. In the present experiments the effect of short-term incubation of preformed normal bone marrow stroma on the adherence of CML derived CFU-BL was studied. For stroma cultures bone marrow cells were cultured in microplates in the presence of hydrocortisone. Cultures were used when stromal layers became confluent and no sign of haemopoiesis could be observed. CFU-BL were studied by panning plastic non-adherent mononuclear (PNAMNC) bone marrow or blood cells. 8.9 +/- 2.4 colonies/103 PNAMNC (six experiments) were formed from normal bone marrow on stromal layers and 4.8 +/- 2.1 colonies/103 PNAMNC (five experiments) from CML bone marrow. Colony formation from normal bone marrow was not increased if stromal layers were incubated with 100 ng/mL granulocyte colony-stimulating factor (G-CSF) or stem cell factor (SCF). Incubation of stroma with G-CSF or SCF, however, increased the colony formation of PNAMNC from CML bone marrow or blood significantly. These findings suggest that local concentration of haemopoietic growth factors at the time of panning may influence the attachment of CML progenitors to the stroma.

Bone Marrow↗
PubMed2000

[Immunophenotyping in acute leukemia: detection of minimal residual disease].

Immunophenotyping improves both accuracy and reproducibility of the acute leukaemia classification and is considered particularly useful for identifying poorly differentiated subtypes of acute myeloid leukaemia and lineage association of acute lymphoid leukaemia. Immunological studies of leukaemic blasts has become critical also identifying biphenotypic leukaemias and acute myeloid leukaemia expressing lymphoid associated markers. At present, while the prognostic value of individual antigen expressions is still controversial, the immunologic detection of minimal residual disease seems to be important in monitoring the acute leukaemia patients in remission. In the present study immunophenotyping of bone marrow samples of 42 patients with acute myeloid leukaemia and 13 patients with acute lymphoid leukaemia was analysed. Patients were assessed both before and after treatment by immunophenotyping, cytogenetics and polymerase chain reaction amplification. The immunophenotyping have allowed more sensitive definition of acute leukaemia relapse, but molecular genetic methods are recommended for detection of elimination of residual disease.

Adolescent↗
PubMed2000

Human health risk assessment and management in hazardous waste site contaminated by polychlorinated benzenes.

The improper management of large quantity of chemical waste of a chemical plant caused considerable soil contamination on a temporary hazardous waste disposal site. Initial and action-oriented exposure and health risk assessment was carried out in early 90's. The dominant contaminants were tetrachlorobenzenes (TeCBs), pentachlorobenzene and hexachlorobenzene (HCB). Concentration of TeCBs in top soil layer and vadoze zone exceeded several g/kg. After taking appropriate technical measures quantitative health risk assessment was performed for the target population living in the surrounding settlements. Health risk estimates to HCB ingested or inhaled with suspended dust and soil particulates showed that carcinogenic risk values lower than 10(-6) i.e. below the acceptable risk. For other chlorobenzenes that cause non-cancer toxic effects risk quotients showed marked health hazard inside the dump and small potential risk in vicinity. However, this assessment is based on limited monitoring data, additional information is needed to substantiate this conclusion.

Benzene Derivatives↗
PubMed2000

Sensitivity analysis of risk assessment programs to various input parameters.

HESP 2.b risk assessment program was studied in detail concerning the effect of changing different input parameters for the output ADI values calculated by the program. We used the standard Netherlands 1.0 scenario offered by the program. With this we fixed a lot of input parameters which define the area, human and animal recipient parameters etc. The remaining 31 unfixed parameters were fixed at first to "BASE" input values and the BASE output values were calculated by HESP. Later we chose only one parameter at a time and changed it to an another value. The calculated ADI values were then compared to BASE output values. Seven parameters (soil type, soil usage, site length, soil pH, groundwater fraction in drinking water, basement floor type and Qev) were studied. We found, that changing soil pH or Qev have not any influence on the output ADI values in case of any contaminant. Soil type change has not any effect on the output ADI value in case of Pb or Cd but it seems to play important role in all cases of the four organic material we investigated. Changing soil usage have influence on the output ADI value almost in every case. It seems to be linear relation between the maximal concentration of contaminant and calculated ADI. Changing the site length and basement floor type gave in some cases different ADI values compared to BASE values. If we alter the groundwater fraction in drinking water we got usually different ADI values. With Risc Human risk assessment program we got similar results: nor the changes in soil type, site diameter or soil pH gave any changes in output ADI values. Our results hint that using HESP and Risc Human requires enhanced caution.

Adult↗
PubMed1997

Expression of syndecan-1 in human B cell chronic lymphocytic leukaemia.

Syndecan-1 is considered an important transmembrane proteoglycan in cell-microenvironment interactions, but its exact function in normal or in transformed B cells is still unknown. In this study, RNA was isolated from peripheral cells of chronic lymphocytic leukaemia (B-CLL) and 'normal', non-leukaemic patients, as controls. Reverse PCR showed no or very low syndecan-1 mRNA expression in controls, while in 11/13 B-CLL the circulating leukaemic cells expressed syndecan-1. Similar results were obtained for interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6). Furthermore, syndecan-1 protein was detected in the majority of circulating B-CLL cells by flow cytometry and immunocytochemistry using anti-syndecan-1 MAb. Control cells were practically negative. Further study is required to understand the biological significance of syndecan-1 on B-CLL cells.

Adult↗
PubMed1988

The kinetics of cell division in a synchronizing fermentor.

The kinetics of cell proliferation of Candida tropicalis synchronized by periodical glucose starvation was examined in a continuous synchronizing fermentor. The length of the deterministic (B) and stochastic (A) phase of the cell cycle was determined by cell density data analysis using the Transition Probability Model. The size distribution of the population shows that the absence of nutrient stops the cells at the beginning of the cell cycle but the succeeding cell divisions are not perfectly synchronized. The reason of this comes from the difference between the generation times of the cells which is the consequence of the different long "A" phases in their cycle.

Candida↗
PubMed1988

Changes of alternative respiration during the division cycle of Candida tropicalis.

The changes in cyanide-resistant and SHAM-sensitive respiration have been examined in the cell cycle of yeast cells synchronized by nutrient starvation. The changing of the cyanide-resistant respiration of cells proliferating in synchronizing fermentor, where the glucose concentration was continuously decreasing, was associated with the stage in cell cycle rather than with the alteration of environment. The cyanide-resistant alternative respiration may be attributed characteristic of a certain part of the cell cycle termed "A" phase. This hypothesis is supported by the observation that in cultures proliferating, synchronously under constant conditions, the cyanide-resistant respiration changes periodically and reaches its maximum in the "A" phase after the cell division.

Candida↗
PubMed1987

Impaired ristocetin aggregation in myeloma due to binding of the aggregating agent by monoclonal protein--presentation of a case.

In a case of severe IgG kappa myeloma with cryoglobulinaemia usual concentrations of epinephrine, collagen, ADP, arachidonic acid, thrombin and ristocetin caused no aggregation of platelets in platelet rich plasma. However, in contrast to other agents ristocetin induced platelet aggregation in higher concentrations. The investigations showed, that the aggregating activity was inhibited by binding of ristocetin to the abnormal protein. Following saturation of the monoclonal protein, the surplus ristocetin caused normal aggregation. This indicates that platelets actually preserved their responsiveness to ristocetin. Possible causes of the phenomenon are discussed.

Aged↗
PubMed1986

Prevention of postoperative thromboembolisms in general surgery by the combination of heparin and dihydroergotamine.

The effect and the degree of safety of administering a fixed combination of 5000 IU of heparin + 0.5 mg dihydroergotamine (HDHE s.c. per every 12 hours) as opposed to 5000 IU of heparin (LDH s.c. every 8 hours) was assessed in a prospective randomized study on 86 patients having undergone major abdominal operation. Postoperatively a deep vein thrombosis was detected by the radiofibrinogen test in 10% of the 40 patients of the HDHE group and in 13% of 46 of the LDH group. Four patients died. At autopsy neither fatal nor a contributing pulmonary embolism was found. 'Non-lethal' pulmonary embolism diagnosed by lung perfusion scintigraphy and by chest X-rays, developed in 2 patients treated with LDH and in one treated with HDHE. Two-thirds of the dose of heparin were identically effective in prevention of venous thromboembolisms than the whole dose if heparin was combined with DHE. The decrease of the heparin dose significantly reduced the number of wound haematomas and of suffusion due to injection.

Adult↗
PubMed1983

Topo-optical reactions of the human blood platelet membrane.

The polarization optical analysis of human blood platelets was carried out by means of topo-optical staining reactions. Similar studies have not been performed so far. With this approach we were able to demonstrate the spatially oriented nature of glycoprotein components in the platelet membrane. Using a sialic acid specific topo-optical reaction the sialic acid component of human platelet membrane was selectively demonstrated and the even distribution of sialic acid residues on the membrane surface was also suggested. Polarization optical analysis has shown a membrane-parallel orientation of oligosaccharide chains carrying sialic acids.

Blood Platelets↗
PubMed1983

Polarization optical investigation by topo-optical reactions of various blood platelet aggregates.

Phases I and II (early and advanced) of platelet aggregation could readily be followed and studied by various topo-optical reactions. Our studies indicate that in the early stage (monitored by an aggregometer) aggregates show no alteration in membrane structure of platelet. In the advanced stage (phase II), in addition to membrane alteration, platelets 2-3 times larger than in the control were observed. These were stained selectively in the pH 1-2 range with thiazine dyes. After hyaluronidase digestion they lost the ability to stain and became birefringent. The elucidation of this phenomenon requires further study.

Blood Platelets↗
PubMed1979

Intrarenal distribution of renal blood flow in the rat.

Intrarenal blood flow distribution was studied with the simultaneous use of the 99Tc labelled frog erythrocyte (microsphere) and the radioactive 86Rb fractionation method in the rat. The amount of blood entering the outer cortex (99Tc labelled erythrocytes method) proved to be higher than one perfusing the outer cortex (86Rb method), whereas the amount of blood entering the inner cortex (99Tc method) was less than the amount perfusing the inner cortex and medulla (86Rb method). Hence a group of the preglomerular arterioles in the outer cortex contributes to the blood supply of the inner cortex, on the other hand a group of preglomerular arteries in the inner cortex participates in the postglomerular blood supply of the medulla. Changes in the renal circulation are, however, associated with altered distribution of postglomerular vascular segments supplied by some groups of preglomerular arterioles. From this it is concluded that the postglomerular vessels of the deeper cortical layers constitute a system which is not parallelly coupled but comprises both series- and parallel-coupled sections. The contribution of these sections appears to vary depending on the actual haemodynamic conditions.

Animals↗